Activate include for Beats highlights (#1311)

Author: dedemorton

docs/en/install-upgrade/highlights.asciidoc

@@ -34,7 +34,7 @@ coming[8.0.0]
 
 This list summarizes the most important enhancements in {beats} {minor-version}.
 
-//include::{beats-repo-dir}/release-notes/whats-new.asciidoc[tag=notable-highlights]
+include::{beats-repo-dir}/release-notes/whats-new.asciidoc[tag=notable-highlights]
 
 [[elasticsearch-highlights]]
 === {es} highlights